If it is offline, validate it with the CCX Database service status as shown in CCX Serviceability.

If DB service is running but the datasource appears offline, log in to Cisco Unified Intelligence Center as the Application Administrator, click Edit Datasource and verify the datasource configuration.

Do not update any parameter in the Edit Datasource page. Instead, to reconfigure the datasource to point to the proper values, go to AppAdmin > Tools > Historical Reporting > Reporting Configuration, and then click Update without changing any configuration. This resets the datasource with proper configuration.